Heat pipe and method to embed a heat pipe in a product

Abstract

A heat pipe (10) for cooling an electronic device, especially a component carrier (100), that comprises a central section (13) with a cavity (12) filled with a heat transfer fluid (20). In longitudinal direction (11) of the heat pipe (10) directly connected with the central section (13) are a first end section (14) on a first end of the central section and a second end section (15) on the opposite second end of the central section, wherein the first end section and the second end section each comprise a landing structure (17) with a surface length (SL, SL.sub.1, SL.sub.2) and a surface width (SW, SW.sub.1, SW.sub.2) and wherein each landing structure is thermoconductively coupled with the central section of the heat pipe. A component carrier comprising at least one heat pipe for cooling it, and a method for producing the component carrier are also provided.

Claims

1. A heat pipe (10) for cooling an electronic device comprising: a central section (13) with a cavity (12) filled with a heat transfer fluid (20), wherein in a longitudinal direction (11) of the heat pipe (10) directly connected with the central section (13) are a first end section (14) on a first end of the central section (13) and a second end section (15) on the opposite second end of the central section (13), wherein the first end section (14) and the second end section (15) each comprise a landing structure (17) distal to the cavity and having a surface length (SL, SL.sub.1, SL.sub.2) and a surface width (SW, SW.sub.1, SW.sub.2), wherein each landing structure (17) is thermoconductively coupled with the central section (13) of the heat pipe (10), wherein each end section (14, 15) is made of flattened and pressed solid copper or solid copper alloy and has a greater width relative to the central section (13), wherein the heat pipe (10) is a single separate part configured to be embedded within a component carrier (100), wherein the heat pipe is already operational before being embedded within the component carrier (100), wherein the component carrier (100) is a printed circuit board, an intermediate printed circuit board product, or an IC-substrate, and wherein the first and second end sections are: (i) structures attached respectively to each of the first and second ends of the central section, or (ii) structures integrally formed with the central section, and wherein the heat pipe (10) is configured to be embedded within the component carrier (100) as an integral unit.

2. The heat pipe (10) of claim 1, wherein the at least one landing structure (17) adjoins or laterally protrudes along at least one of a longitudinal segment of the central section (13), the first end section (14), and the second end section (15).

3. The heat pipe (10) of claim 1, wherein at least one landing structure (17) is electrically coupled with the central section (13) of the heat pipe (10).

4. The heat pipe (10) of claim 1, wherein the first end section (14) or the second end section (15) is firmly bonded with the central section (13).

5. The heat pipe (10) of claim 1, wherein at least one of the central section (13), the first end section (14), and the second end section (15) has or have, respectively, a cylindrical profile (16) with an outer diameter (D) of the heat pipe (10).

6. The heat pipe (10) of claim 1, wherein at least one of the first end section (14) and the second end section (15) is or are, respectively, made of a solid metal.

7. The heat pipe (10) of claim 1, wherein a height (h) of the flattened landing structure (17) is smaller than a total height (H) or diameter (D) of the central section (13) of the heat pipe (10) and wherein the surface width (SW, SW.sub.1, SW.sub.2) of the flattened landing structure (17) is greater than the total height (H) or diameter (D) of the central section (13) of the heat pipe (10).

8. A component carrier (100) comprising at least one heat pipe (10) according to claim 1, wherein the at least one heat pipe (10) is embedded within at least one inner layer (111, 112, 113) of the component carrier (100), which at least one inner layer (111, 112, 113) is arranged between outside surface layers (110) forming the outside surface of the component carrier (100), and wherein each landing structure (17) of the embedded heat pipe (10) is thermoconductively coupled (A.sub.1, A.sub.2, A.sub.3) by means of at least one thermal via (30) to at least one outside surface of an outside surface layer (110) of the component carrier (100).

9. The component carrier (100) of claim 8, wherein at least one thermal via (30) contacts a landing structure (17) on its surface or ends within the landing structure (17) or passes through the landing structure (17).

10. The component carrier (100) of claim 8, wherein each landing structure (17) is electrically coupled or galvanically coupled by means of at least one thermal via (30) to at least one outside surface of an outside surface layer (110).

11. The component carrier (100) of claim 8, further comprising at least one heat-dissipating component (120, 130) and at least one heat-releasing component (125, 36), wherein the at least one heat-dissipating component (120) is mounted on an outside surface layer (110) or is embedded (130) within at least one inner layer (111, 112, 113) and contacted directly or by means of at least one thermal via (30) to at least one of a landing structure (17) of the first end section (14), the central section (13), and the second end section (15) of the embedded heat pipe (10) and wherein a landing structure (17) of at least one of the first end section (14), the central section (13) and the second end section (15) of the heat pipe (10) is contacted directly or by means of at least one thermal via (30) to the at least one heat-releasing component (125, 36) which is mounted on an outside surface layer (110) or embedded within at least one inner layer (111, 112, 113).

12. The component carrier (100) of claim 11, wherein the at least one heat-dissipating component (120, 130) is contacted directly or by means of at least one thermal via (30) to a landing structure (17) of the central section (13) of the embedded heat pipe (10) and wherein heat releasing components (125, 36) are contacted by means of thermal vias (30) to landing structures (17) of at least one of the first end section (14) and second end section (15) of the heat pipe (10).

13. The heat pipe of claim 1, wherein the first end section, second end section, and central section are manufactured in one piece such that the first and second end sections are integrally formed with the central section.

14. The heat pipe of claim 13, wherein the central section is cylindrical.

15. The heat pipe of claim 14, wherein each of the first and second end sections is cylindrical.

16. The heat pipe of claim 13, wherein each of the first and second end sections comprises a conically tapered headpiece.

17. The heat pipe of claim 1, wherein the first and second end sections are attached respectively to the first and second ends of the central section by an interlocking connection or a bonded connection, which are selected from a plug connection, welding, gluing, or soldering.

18. The heat pipe of claim 1, wherein the central section has a diameter of less than 1 mm.

19. The heat pipe (10) of claim 1, wherein the central section (13) has a cylindrical profile.

20. An electronic component assembly comprising: a component carrier selected from a printed circuit board (PCB), an intermediate PCB, and an IC-substrate; one or more heat pipes embedded in the component carrier, wherein at least one of the heat pipes comprises (i) a central section with a cavity filled with a heat transfer fluid, (ii) a first end section on a first end of the central section, and (iii) a second end section on the opposite second end of the central section, wherein the first and second end sections each comprises a landing structure integrally formed with, and thermoconductively coupled to, the central section, wherein the first end section, second end section, and central section are manufactured in one piece such that the first and second end sections are integrally formed with the central section, wherein each end section is made of flattened and pressed solid copper or solid copper alloy and has a greater width relative to the central section, wherein each of the one or more heat pipes is a single separate part configured to be embedded in the component carrier as an integral unit, and wherein each of the one or more heat pipes is already operational before being embedded within the component carrier; and at least one thermal via extending into the component carrier and thermoconductively coupled to one of the landing structures and to at least one heat dissipating component.

21. A heat pipe (10) for cooling an electronic device comprising: a central section (13) with a cavity (12) filled with a heat transfer fluid (20), wherein in a longitudinal direction (11) of the heat pipe (10) directly connected with the central section (13) are a first end section (14) on a first end of the central section (13) and a second end section (15) on an opposed second end of the central section (13), wherein the first end section (14) and the second end section (15) each comprise a landing structure (17) distal to the cavity and having a surface length (SL, SL.sub.1, SL.sub.2) and a surface width (SW, SW.sub.1, SW.sub.2), wherein each landing structure (17) is thermoconductively coupled with the central section (13) of the heat pipe (10), wherein each end section (14, 15) is made of flattened and pressed solid copper or solid copper alloy and has a greater width relative to the central section, wherein the first end section, second end section, and central section are manufactured in one piece such that the first and second end sections are structures integrally formed with the central section, wherein the heat pipe (10) is a single separate part configured to be embedded within a component carrier (100) as an integral unit, and wherein the heat pipe (10) is already operational before being embedded within the component carrier (100).

Description

(1) Other objects, advantages and novel features of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying schematic drawings:

(2) FIG. 1 refers to the known art and shows in a cross-sectional view a detail of a printed circuit board comprising a heat pipe that is partly connected to thermal vias;

(3) FIG. 2 shows in a top view a detail of a first embodiment of a heat pipe according to the invention with a landing structure to easily contact thermal vias;

(4) FIG. 3 shows in a cross-sectional side view the first embodiment of a heat pipe according to FIG. 2;

(5) FIG. 4 depicts in a partial sectional side view a first embodiment of a component carrier, for example an intermediate printed circuit board, according to the invention with a heat pipe as shown in FIG. 3 embedded and with thermal vias already in place;

(6) FIG. 5 shows in a cross-sectional side view a second embodiment of a heat pipe according to the invention;

(7) FIG. 6 depicts in a partial sectional side view a second embodiment of a component carrier, for example an intermediate printed circuit board, according to the invention with a heat pipe as shown in FIG. 5 embedded and with thermal vias already in place;

(8) FIG. 7 shows in a cross-sectional side view a third embodiment of a heat pipe according to the invention;

(9) FIG. 8 depicts in a partial sectional side view a third embodiment of a component carrier, for example an intermediate printed circuit board, according to the invention with a heat pipe as shown in FIG. 7 embedded and with thermal vias already in place;

(10) FIG. 9 shows in a cross-sectional side view a central section of a heat pipe with tangential adjoining landing structures;

(11) FIG. 10 shows in a cross-sectional side view a central section of a heat pipe with radial protruding landing structures;

(12) FIG. 11 displays in an aerial view a heat pipe with radial protruding landing structures on its end sections;

(13) FIG. 12 displays in an aerial view a heat pipe with radial protruding landing structures on its end sections as well as on its central section;

(14) FIG. 13 depicts the contact deep milling process to drill holes from the outside surface layer of an intermediate printed circuit board to contact landing structures of one embedded heat pipe;

(15) FIG. 14 shows in a sectional side view another fourth embodiment of a component carrier according to the invention with a complex structure; and

(16) FIG. 15 depicts in a sectional side view another fifth complex embodiment of a component carrier according to the invention.

(17) In FIG. 1 that refers to the known art a cross-section of a heat pipe 10 that is integrated within a printed circuit board 100 is shown. The printed circuit board 100 embodies a component carrier 100. The heat pipe 10 comprises a cavity 12 that is filled with a heat transfer fluid 20 like acetone or water. The heat pipe 10 has a cylindrical shape with a diameter D and a wall thickness W. The heat pipe 10 is manufactured for example of copper and is partly connected to thermal vias 30 that are here for example vias 32 filled with copper. The thermal vias 30 have a diameter T. As depicted in FIG. 1 the round and cylindrical, respectively, shape of the heat pipe 10 causes several problems for the connection with the thermal vias 30.

(18) Hitting this structure of the heat pipe 10 for instance with a laser drillerwhich laser driller is not depictedis difficult since the projected surface area of the heat pipe 10 seen from an outside surface layer 110 area of the printed circuit board 100 is small. Thus several thermal vias 30 will inevitably not be contacted and simply miss the surface of the heat pipe 10 in the manufacturing process.

(19) In FIG. 1 the thermal via 30 on the upper left side of the figure contacts the heat pipe in the centre of the heat pipe 10. This thermal via 30 on the left properly contacts the outer surface of the heat pipe 10. Nevertheless, when one moves outwards the centre of the heat pipe 10 as shown in the case of the thermal via 30 on the upper right side of the figure, the contact surface of the heat pipe 10 with the thermal via 30 is minimized due to the geometrical effect of the cylindrical surface of the heat pipe 10. This inevitably results in bad thermal and electrical contacts as well as in weak mechanical stability of the contact between the copper filled via 32 and the heat pipe 10.

(20) FIG. 2 shows in a top view a detail of a heat pipe 10 according to the invention. A central section 13 of the heat pipe 10 having a cylindrical profile 16 with a diameter D is connected with a first end section 14 of the heat pipe 10 having a landing structure 17 to easily contact thermal vias 30. The shown landing structure 17 is made up of a flattened and pressed end section of solid copper with a surface length SL, respectively SL.sub.1, and a surface width SW, respectively SW.sub.1, of the landing structure 17. As the landing structure 17 is arranged on the first end section 14, the surface length SL of this first end landing structure 17 is indicated also with reference sign SL.sub.1. Vice versa is the surface width SW here also indicated with the respective reference sign SW.sub.1 to indicate herewith unambiguously the surface width SW.sub.1 of the first end landing structure 17. In FIG. 2 not shown is a respective second end section 15 of the heat pipe 10 on the opposite end in regard to the first end section 14.

(21) FIG. 3 that shows in a cross-sectional side view the first embodiment of the heat pipe 10 along its longitudinal axis 11 according to FIG. 2 indicates also this second end section 15 of the heat pipe 10. Also the second end section 15 comprises a landing structure 17 that is made up of a flattened and pressed end section of solid copper with a surface length SL.sub.2 and a surface width SW.sub.2 of the respective landing structure 17. It can easily be seen in FIG. 2 thatcompared with the known art of FIG. 1by enlarging the landing structure 17 the feasibility to safely connect thermal vias 30 is significantly increased. As consequence thereof heat dissipation capacity of suchlike heat pipes 30 is improved and thermal conduction between thermal vias 30 and the heat pipe 10 is enhanced. In FIG. 3 it can be seen that the first 14 and second 15 end sections each comprising the landing structures 17 are flattened and have a reduced height h of the landing structure 17. The central section 13 of the heat pipe 14 that comprises a cavity 12 filled with a heat transfer fluid 20 has a total height H. As the central section 13 has a cylindrical profile 16 the total height H corresponds to the diameter D of the central section 13. The total length L of the heat pipe 10 along its longitudinal axis 11 corresponds to the sum of length of sections 13, 14 and 15 of the heat pipe 10.

(22) FIG. 2 shows for easier understanding the thermal vias 30 already in placeevenly positioned on the landing structure 17. This enlarged landing structure 17 will also allow an easier aligning process for the laser drill, which in turn means a more efficient thermal and also electrical connection of the thermal vias 30 to the heat pipe 10.

(23) FIG. 4 depicts in a partial sectional side view a first embodiment of a component carrier 100 like an intermediate printed circuit board 100 according to the invention with a heat pipe 10 as shown in FIG. 3 embedded and with thermal vias 30 already in place. As can be schematically seen the intermediate printed circuit board 100 comprises outside surface layers 110 forming its outer surfaces and several inner layers 111, 112 and 113. The intermediate printed circuit board 100 thus is a multilayer circuit board 100 wherein the pre-fabricated heat pipe 10 as shown in FIG. 3 has yet been embedded while manufacture of the intermediate printed circuit board 100. To receive a finished printed circuit board for example structured solder layers that preferably are arranged on the outer surfaces of the outside surface layers 110 are not yet applied. Optionally the outer surfaces of a ready-made printed circuit board are also finished which is also not the case for the shown intermediate printed circuit board 100.

(24) In FIG. 4 a first electronic component 120 and a second electronic component 125 are schematically indicated each with dotted lines. The first electronic component 120 is arranged on the top outside surface layer 110 above the first end section 14 of the embedded heat pipe 10. The electronic component 120 which is a heat-emitting component 120 is contacted via several thermal vias 30here with vias 32 filled with copperto the flattened landing structure 17 of the first end section 14 of the heat pipe 10. Contact areas 36 that are arranged on the outside surface layers 110 between several thermal vias 30 enhance the convenience to electrically and thermally contact the respective electronic components 120, 125 with the thermal vias 30. The larger landing structure 17 will also allow an easier aligning process for the laser drill, which in turn means a more efficient thermal and/or electrical connection of the thermal vias 30 to the heat pipe 10. The cylindrical 16 central section 13 of the heat pipe 10 is connected directly to the flattened pieces of metal or copper, respectively, forming the landing structures 17. The landing structures 17 are directly contacted to the respective thermal vias 30, for example copper-filled vias 32 and/or plated through holes 34.

(25) The flattened part of the landing structures 17 can be produced during the manufacturing process of the heat pipe 10 simply by pressing the copper cylinder and welding the parts after enclosing the heat transfer fluid 20, for example water. Alternatively the landing structures 17 can also be bonded to the structure of the heat pipe 10 after the manufacturing process or even be inserted in the PCB during the manufacturing process. For example the landing structures 17 can also be made by attaching thermal conductive inlays like copper inlays to the end sections of the heat pipe 10 as well.

(26) In direction of the longitudinal axis 11 on the opposite end of the heat pipe 10 the second electronic component 125 is arranged on the bottom outside surface layer 110 of the intermediate printed circuit board 100. The bottom outside surface layer 110 is arranged on the opposite outside surface of the intermediate printed circuit board 100 in respect to the top outside surface layer 110. The second electronic component 125 which is a heat releasing component 125 is here contacted with thermal vias 30 to the landing structure 17 of the second end section 15 of the heat pipe 10. These thermal vias 30 are carried out as plated through holes 34. To cool the heat-dissipating electronic component 120 a heat input A.sub.1 that is schematically indicated as arrow A.sub.1 is conducted via the copper-filled vias 32 to the first end section 14 and further to the central section 13 of the heat pipe 10, wherein the heat is further conducted via the heat transfer fluid 20 within the cavity 12 in heat conduct direction A.sub.2 to the second end section 15. At the second end section 15 the heat is conducted via the plated through holes 34 to the bottom outside surface layer 110 of the printed circuit board 100 and is then released via the electronic component 125 into the surroundings of the intermediate printed circuit board 100 which is indicated via an arrow A.sub.3 representing the heat output A.sub.3.

(27) FIG. 5 shows in a cross-sectional side view a second embodiment of a heat pipe 10 according to the invention. In this embodiment the first end section 14 and the second end section 15 of the heat pipe 10 both have the same cylindrical profiles 16 with a diameter D as is the case with the cylindrical central section 16. Advantageously the landing structures 17 of the first end section 14 and second end section 15, respectively, are lengthwise 11 extended and have surface lengths SL.sub.1 and SL.sub.2, respectively. The first end section 14 and the second end section 15 are both made of solid copper. Thus contacting of thermal vias within the landing structures 17 of the heat pipe 10 is easy and reliable. To illustrate the dimensions of this heat pipe 10 as shown in FIG. 5 the total length L of the heat pipe 10 is for example 890 mm, the surface lengths SL.sub.1 and SL.sub.2 of the respective landing structures 17 are approximately 10 mm and the diameter D of the heat pipe 10 is here 1.5 mm.

(28) FIG. 6 illustrates in a partial sectional side view a second embodiment of a component carrier 100, an intermediate printed circuit board 100 according to the invention with a heat pipe 10 as shown in FIG. 5 embedded and with thermal vias 30 already in place. Due to the lengthwise extended landing structures 17 a proper thermal connection between the thermal vias 30 and the heat pipe 10 is ensured.

(29) FIG. 7 shows in a cross-sectional side view a third embodiment of a heat pipe 10 according to the invention. In this heat pipe embodiment the landing structures 17 of the first end section 14 and the second end section 15 each show a conically tapering headpiece. The first end section 14 and the second end section 15 both are made of solid copper.

(30) FIG. 8 depicts in a partial sectional side view a third embodiment of a component carrier 100, here an intermediate printed circuit board 100, according to the invention with a heat pipe 10 as shown in FIG. 7 embedded and with thermal vias 30 already in place. Due to the lengthwise extended landing structures 17 a proper thermal connection between the thermal vias 30 and the heat pipe 10 is ensured also in this embodiment. To illustrate the dimensions of this heat pipe 10 as shown in FIG. 8 the total length L of the heat pipe 10 is for example 900 mm, the surface lengths SL.sub.1 and SL.sub.2 of the respective landing structures 17 are approximately 20 mm and the diameter D of the heat pipe 10 is here 1.0 mm.

(31) FIG. 9 shows in a cross-sectional side view a central section 13 of a heat pipe 10 with tangential adjoining landing structures 17 that enlarge the surface width SW and thus the surface area of the heat pipe 10.

(32) FIG. 10 shows in a cross-sectional side view a central section 13 of a heat pipe 10 with radial protruding landing structures 17.

(33) FIG. 11 displays in an aerial view a heat pipe 10 with radially protruding landing structures 17 that are attached on the first end section 14 as well as on the second end section 15.

(34) FIG. 12 displays in an aerial view another heat pipe 10 according to the invention with radially protruding landing structures 17 on its end sections 14, 15 as well as on its central section 13.

(35) FIG. 13 depicts the contact deep milling process to drill via a drilling device 150 opening holes 155which are here drill holes 155from the outside surface layer 110 of an intermediate printed circuit board 100 to contact landing structures 17 of one embedded heat pipe 10. In this said process the heat pipe 10 can be connected directly via a controlled drilling system. In this process, the embedded heat pipe 10 has to be connected to an electrical circuit 140 which is closed when a drilling device 150 like a driller enters in contact with the outer surface of the embedded heat pipe 10. While drilling the intermediate printed circuit board 100, when the drilling device 150 touches the outside of the heat pipe 10, the applied electric circuit 140 is closed which is indicated for example by an amperemeter 160. Thus the drilling device 150 immediately stops penetrating the PCB structure 100. This process can be controlled by a factor of approximately 20 m (micrometres) in depth and does not damage the heat pipe 10 walls W. The embedded heat pipe 10 can afterwards be contacted via a galvanic copper process with the electrical network of the intermediate printed circuit board 100. By this convenient way of manufacture, the heat pipe 10 can be directly connected to the outside surface layer 110 of the intermediate printed circuit board 100 via galvanic copper vias 30 and contact areas 36, respectively.

(36) FIG. 14 shows in a sectional side view another fourth embodiment of a component carrier 100 according to the invention. The component carrier 100 is here for example an intermediate printed circuit product 100 with a complex structure. A heat pipe 10 comparable to the one as shown in FIG. 11 is yet embedded and with thermal vias 30 already in place. An electronic component 120 is arranged on the bottom outside surface layer 110 of the component carrier 100 and is directly connected via thermal vias 30 with the landing structure 17 of the first end section 14 of the embedded heat pipe 10. The electronic component 120 which is a heat-emitting component 120 is contacted via several thermal vias 30 to the flattened landing structure 17 of the first end section 14 of the heat pipe 10. Another electronic component 130 which is also a heat-dissipating component is embedded within the component carrier 100 and is directly attached onto the landing structure 17 of the first end section 14. On the second end section 15 of the heat pipe 10 its landing structure 17 is connected via thermal vias 30 to contact areas 36 that are arranged on the top and bottom outside surfaces of the component carrier 100.

(37) To cool the heat-dissipating electronic component 120, a heat input A.sub.1 that is schematically indicated as arrow A.sub.1 is conducted via the copper-filled vias 32 to the first end section 14 and further to the central section 13 of the heat pipe 10, wherein the heat is further conducted via the heat transfer fluid 20 within the cavity 12 in heat conduct direction A.sub.2 to the second end section 15. Also the heat of the heat-emitting embedded electronic component 130 is transported in heat conduction direction A.sub.2 from the heat-dissipating first end section 14 to the heat-releasing, cooler end section 15 of the heat pipe 10. At the second end section 15 the heat is conducted via plated through holes 34 to the bottom outside surface layer 110 of the printed circuit board 100 and is then released via the contact areas 36 into the surroundings of the intermediate printed circuit board 100 which is indicated via an arrow A.sub.3 representing the heat output A.sub.3.

(38) FIG. 15 depicts in a sectional side view another fifth complex embodiment of a component carrier 100 according to the invention. The component carrier 100 is here for example an intermediate printed circuit product 100. A heat pipe 10 comparable to the one as shown in FIG. 12 is yet embedded and with thermal vias 30 already in place. An electronic component 120 is arranged on the bottom outside surface layer 110 of the component carrier 100 and is directly connected via thermal vias 30 with the landing structure 17 of the central section 13 of the embedded heat pipe 10. The electronic component 120 which is a heat-emitting component 120 is contacted via several thermal vias 30 to the central section 13. Another electronic component 130 which is also a heat-dissipating component is embedded within the component carrier 100 and is directly attached onto the landing structure 17 of the central section 13. On the first end section 14 as well as on the second end section 15 of the heat pipe 10 the respective landing structures 17 each are connected via thermal vias 30 to contact areas 36 that are arranged on the outside surfaces of the component carrier 100.

(39) To cool the heat-dissipating electronic component 120, a heat input A.sub.1 that is schematically indicated as arrow A.sub.1 is conducted via for instance copper-filled vias 32 to the central section 13 and further from the central section 13 to both end sections 14, 15 of the heat pipe 10. Thus the emitted heat is further conducted via the heat transfer fluid 20 within the cavity 12 in heat conduct direction A.sub.2as marked with a double arrow A.sub.2to the first end section 14 and also to the second end section 15. Also the heat of the heat-emitting embedded electronic component 130 is transported in heat conduction direction A.sub.2 from the heat-dissipating central section 13 to the heat-releasing, cooler end sections 14, 15 of the heat pipe 10. At the first end section 14 and second end section 15 the heat is conducted via plated through holes 34 to the bottom outside surface layer 110 of the printed circuit board 100 and is then released via contact areas 36 into the surroundings of the intermediate printed circuit board 100 which is indicated via arrows A.sub.3 representing the heat output A.sub.3. In this embodiment a heat-sensitive component 121 is positioned on the upper outside surface of the intermediate printed circuit board 100. Although this heat-sensitive component 121 is not directly connected to the heat pipe 10, the heat pipe 10 protects also this heat-sensitive component 121 from the off-heat produced by the heat-emitting embedded electronic component 130. Thus the heat pipe 10 works as a heat bus and conducts the off-heat of component 130 away to prevent heat build-up of the heat-sensitive component 121.

(40) In FIG. 15 the thermal vias 30 of the first end section 14 on the left side of the picture contact the landing structure 17 on its surface. The thermal vias 30 of the second end section 15 on the right side of the picture pass through the landing structure 17.

LIST OF REFERENCE SIGNS

(41) 10 heat pipe 11 longitudinal axis 12 cavity 13 central section of heat pipe 14 first end section of heat pipe 15 second end section of heat pipe 16 cylindrical profile of central section 17 landing structure 20 heat transfer fluid 30 thermal via 32 via filled with metal (copper) 34 plated through hole 36 contact area 100 component carrier; (intermediate) printed circuit board; IC substrate 110 outside surface layer of printed circuit board 111 inner layer of printed circuit board (resp. 112, 113) 120 electronic component; heat-dissipating component 121 heat-sensitive component 125 electronic component; heat-releasing component 130 embedded component 140 closed electric circuit 150 drilling device, driller 155 opening hole, drill hole 160 amperemeter A.sub.1 heat input (arrow) A.sub.2 heat conduct (arrow) A.sub.3 heat output (arrow) D diameter of heat pipe H total height of heat pipe h height of landing structure L total length of heat pipe SL surface length of landing structure (resp. SL.sub.1, SL.sub.2) SW surface width of landing structure (resp. SW.sub.1, SW.sub.2) T diameter of thermal via W wall thickness of central section of heat pipe